I usually figure if it's more than ten minutes, it's quicker and healthier on the stovetop than in the microwave.

My failsafe* method for a single serving of old-fashioned oats is 7 minutes at 40% power. No stir, no boilover.

(*presuming the large bowl jobob mentioned - a 28 oz Corningware bowl works just fine for 1/3 c oats and 1 c water, with or without dried fruit)